Thermodynamic Experiments and Modelling of Cyclopentane Hydrates in the Presence of NaBr, KBr, K2SO4, NaBr–KBr, NaCl–NaBr, KCl–KBr, Na2SO4–K2SO4, and CaCl2–MgCl2

Water shortage has been a serious issue for many years. Hydrate-based desalination (HBD) technology is a potential candidate for this solution. The present study investigates the use of Cyclopentane (CP) as a hydrate former for desalination through crystallization at low temperatures and atmospheric pressure. The primary objective of this work is to provide phase equilibrium data for CP hydrates (CPH) in the presence of novel salt systems, including NaBr, KBr, K2SO4, NaBr–KBr, NaCl–NaBr, KCl–KBr, Na2SO4–K2SO4, and CaCl2–MgCl2. Phase equilibrium temperatures were determined using both rapid and slow dissociation procedures. The van der Waals and Platteeuw-based Kihara (Kihara) approach, Hu-Lee-Sum (HLS) correlation, Standard Freezing Point Depression (SFPD) approach, and Activity-Based Occupancy Correlation (ABOC) were applied to model these new experimental data. The experimental results demonstrate that the differences between the quick and slow procedure data range from 0 °C to 1.2 °C. In addition, the increasing salt concentration enhances the inhibitory effect on hydrate formation. Furthermore, the influence of cations on the equilibrium temperature follows the decreasing order of Mg2+ > Ca2+ > Na+ > K+. In terms of halide anions, Br− exhibits a stronger impact on equilibrium temperature compared to Cl−. The thermodynamic modeling results (for all four models) show good agreement with the experimental data with the average absolute deviation (AAD) of less than or equal to 0.79 °C. The ABOC approach proves to be the most effective among the four methods evaluated for accurately reproducing the equilibrium temperature of CPH, with AAD less than or equal to 0.38 °C.